Extraction And Separation Of Several Natural Active Substances By Ionic Liquids

Ionic liquids (liquids Ionic) have stable physical and chemical properties. And the polarity of the ionic liquids could be regulated by changing the structure of the anions and cations of its. Most of hydrophilic ionic liquids can not only to form aqueous two phase systems with certain salts or some non-organic solvent-based compounds, but also to form two-phase systems with some moderately polar organic solvent. These two types of extraction systems have shown excellent performance in the separation of biomolecular and natural medicines. In this paper, aqueous two phase extraction systems of hydrophilic ionic liquid/salt were applied to seperate flavonoids of rutin and luteolin, alkaloids of berberine hydrochloride and dehydrocavidine. The two-phase ternary systems composed of hydrophilic ionic liquids, water and ethyl acetate were used to separate the resveratrol, polydatin and emodin of the polygonum cuspidatum. The separation conditions were optimized by single factor experiments. Therefore, the results of this paper provide a basis for the application of ionic liquids in the selective separation of natural active substances. Details are as follows:(1) Rutin and luteolin were taken as the model molecules to evaluate the separation effect of aqueous two-phase systems composed of ionic liquids/salts. The effects of the types of anions, alkyl chain length of cations of the ionic liquids and the types of salts on the separation were investigated. C2mimBF4/(NH4) 3C6H5O7 was screened out as the optimal ATPS to seperate rutin and luteolin. Additionally, the effects of mass of C2inimBF4 and (NH4)3C6HsO7, temperature, pH and initial total concentration of the substrates on the separation were studied. The results showed that under the optimum conditions of mass of C2mimBF4 of 1.40 g, mass of (NH4)3C6H5O7 of 2.5 g, temperature of 278K, pH of 10.67 and the initial total concentration of the substrates of 2.0 mg·mL-1, the selective coefficient of luteolin to rutin could reach 116.59.(2) Aqueous two-phase systems consist of ionic liquids and salts were used to seperate the dehydrocavidine and berberine from the corydalis saxicola bunting ethanolic extract. The effects of the anions, alkyl chain length of cations of the ionic liquids, the types of salts, temperature and pH on the separation were studied. Under optimized conditions, the selectivity coefficient of dehydrocavidine to berberine was 2.34.(3) The two-phase ternary systems composed of hydrophilic ionic liquids, water and ethyl acetate were used to separate the resveratrol, polydatin and emodin of the polygonum cuspidatum. Experimental results showed that this two-phase ternary system could be well separate polydatin, resveratrol and emodin. Polydatin tended to migrate to the aqueous phase with ionic liquid, while resveratrol and emodin prefered to move to the ethyl acetate phase. under any condition, the resveratrol almost completely separated with the emodin. Under optimized conditions, the selectivity coefficient of polydatin to resveratrol was as high as 404.